Transient coherent emission from anisotropic semiconductors studied with phase-locked pulse pairs

The coherent emission in the direction of the reflection has been investigated under the Brewster angle of incidence by using phase-locked pulse pairs to excite resonantly the excitons in the anisotropic crystal GaSe. The interferogram of the reflected pulse has a long tail corresponding to the free induction decay signal. We also observed the phase difference between the coherent emission from the Γ4 and Γ6 excitonic polarizations in the direction of the reflection.